After 40 weeks of pregnancy, a baby is born

You are special! As unique human beings our lives began at the moment of fertilization. Explore the miraculous facts of our earliest days of life. These 40 weeks of facts are recognized in medical textbooks as well as basic biology books.

Join our educational efforts and share the story of life before and after 40 weeks of pregnancy. By providing a window to life before birth, we can be a voice for those without one.

40 Weeks of Fetal Development

Week 1: Though the baby hasn’t been conceived yet, doctors start the gestational age here, with the end of the mother’s last cycle. What is a calm scene in the womb will soon turn into a show of amazing growth and development over the next nine months.

Week 2: At the end of week two, fertilization occurs and a unique, complete human being with 46 chromosomes detailing her entire development throughout life has entered the world!

Week 3: The baby’s cells are dividing and growing rapidly as she travels down the fallopian tube to implant in the wall of the womb so mother can nourish the developing child.

Week 4: The baby is the size of a period at the end of a sentence, and cells in the baby have separated off to form the placenta which will nourish the child until birth. The baby has already communicated to her mother’s body with hormones to let her know she is growing in the womb.

Week 5: Organ systems are beginning to develop and the baby’s heart starts to beat, just 21 days after fertilization.

Week 6: The baby’s neural tube closes, eventually becoming the fully-formed brain and spinal cord. She is 1/8 of an inch long.

Week 7: Tiny nostrils are visible and the baby’s hands and feet are beginning to take shape.

Week 8: The baby is ½ of an inch long.Only six weeks after coming into existence fingers, ears and eyes can be seen. Taste buds are forming on her tongue and tooth buds are taking shape.

Week 9: The baby has grown a quarter of an inch in just a week and her teeny tiny toes are now visible.

Week 10: The baby’s eyelids close to protect the wonderfully complex eyes while they form. Each minute the baby’s brain develops 250,000 new neurons and she can now move her muscles.

Week 11: The baby is two inches long. She has reached the end of the embryonic stage and is now known as a “fetus,” Latin for “young one.” Her kidneys are developing and produce urine for the first time.

Week 12: Fingernails have begun forming on the baby’s small fingers.

Week 13: Bones are beginning to harden in the baby’s head, arms and legs.

Week 14: The baby is 3 ½ inches long and if we had a window to the womb we could tell if she was a girl or if he was a boy.

Week 15: The baby’s hair pattern on her head is forming. Researchers argue whether her widow’s peak is the result of her genetic code or her own self-directed growth in the womb.

Week 16: An ultrasound at this point would reveal the baby moving her legs and arms and maybe even sucking her thumb. It might also be able to determine her gender.

Week 17: Fat begins to form to keep the baby warm and cozy afterbirth.

Week 18: The baby is 5 ½ inches long and might hear her first sound with her developing ears.

Week 19: A waxy substance called vernix begins to cover the baby’s skin to protect her from the amniotic fluid.

Week 20: Halfway through 40 weeks, the baby’s mother might begin to feel her tiny movements for the first time.

Week 21: The baby is now 10 inches long, measured head to heel. Her digestive system is getting exercise as she swallows amniotic fluid.

Week 22: Hair becomes visible. The baby’s eyebrows might even be visible and her body is covered in small, fine hairs called lanugo to help hold the protective vernix to her skin.

Week 23: We could take the baby’s fingerprints and rapid eye movements start occurring. Is the baby dreaming, and what does a baby in the womb dream about?

Week 24: The baby is almost 12 inches long and has been regularly sleeping and waking. Her mother might be able to guess which she is doing based on her movement.

Week 25: Her mother’s voice or other familiar sounds are recognized by the baby, who responds to them.

Week 26: Lungs are getting stronger in the baby, who is 14 inches long now. Her teeth buds are apparent in her gums.

Week 27: The baby has reached the end of the second trimester. Every major body system is present and has been functioning, and only 13 more weeks of exercise in the womb are needed to make her ready for the wide world.

Week 28: Eyelids have reopened and the baby’s eyelashes are present.

Week 29: The baby’s bones have finished forming, though they are soft in preparation for continued growth.

Week 30: The baby’s eyes are wide open now and she has a full head of hair.

Week 31: The baby’s brain has developed enough to control breathing and her own body temperature independent of mother.

Week 32: The baby’s first haircut happens as lanugo begins to fall off.

Week 33: Small pupils in the baby’s eyes can function, dilating and constricting in dim or bright light.

Week 34: Fingernails have now fully grown out on her fingers as the baby reaches more than a foot and a half in length.

Week 35: In preparation for birth, the baby begins to gain lots of weight, about a half a pound every week.

Week 36: The baby is getting quite cramped in the womb now, but she is still able to move around. What a big change the next month will bring!

Week 37: Almost ready for birth, the baby begins positioning head down in the womb to make birth easier.

Week 38: The baby has a firm grasp with her hands and is considered full-term at this point.

Week 39: While she continues growing in the womb, the baby’s family is anxiously waiting and preparing for the moment they can see her with their own eyes for the first time.

Week 40: The big day arrives and the baby experiences a whole new world on a day forever remembered. It’s an experience more than a million of her fellow babies are deprived of every year in America.

Educational Resources

Prolife Action Center - Our Action Center provides news on current events and legislation, and action items for you to help make a difference.

Educational Resource Centers - Right to Life of Michigan Educational Resource Centers offer a lending library with prolife books and videos, free brochures and pamphlets on life issues, and the latest prolife materials.

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Educational Flyers

Download these half page (5½ x 8½) educational flyers and share the excitement and development of life before birth! Each flyer reminds us that by providing a window to life before birth, we can be a voice for those without one.

Pregnancy Help

If you or someone you know is experiencing an unplanned or crisis pregnancy please call 800-57-WOMAN, a toll-free 24/7 to be connected to a caring, confidential help agency. Or, find a help center near you, we list more than 150 agencies in Michigan on our web site. VIEW LIST